Researchers Use Both "Positive" and "Negative" Evidence to Infer the Roles

Researchers use both "positive" and "negative" evidence to infer the roles of structures in behaviors.Which observation would be considered "negative" evidence in support of a hypothesis about the role of a brain structure?

A) There is an increase in activity in the hippocampus when people are trying to recall a sequence of digits.
B) Upon being groomed,dogs exhibit a decrease in activity of a brain structure associated with fear.
C) Removal of a particular brain structure causes fish to swim less efficiently.
D) Removal of a particular brain structure has no discernible effect on the behavior of a spider.
E) Broca's area of the brain shows increased activity when chimpanzees vocalize.